U.S. patent number 5,055,341 [Application Number 07/485,631] was granted by the patent office on 1991-10-08 for composite molded articles and process for producing same.
This patent grant is currently assigned to Sekisui Kagaku Kogyo Kabushiki Kaisha. Invention is credited to Masahiko Ishida, Masahiro Tsukamoto, Katsuhiko Yamaji.
United States Patent |
5,055,341 |
Yamaji , et al. |
October 8, 1991 |
Composite molded articles and process for producing same
Abstract
A composite molded article made of a nonwoven fibrous mat
wherein inorganic monofilaments having a length of 10 to 200 mm and
a diameter of 2 to 30 micrometers are partially bonded with a
thermoplastic resin binder, may voids being provided throughout the
mat and a large number of fine holes communicating with the voids
in the inside being formed in at least one surface of the mat; and
processes for producing the same.
Inventors: |
Yamaji; Katsuhiko (Kyoto,
JP), Ishida; Masahiko (Yokohama, JP),
Tsukamoto; Masahiro (Takatsuki, JP) |
Assignee: |
Sekisui Kagaku Kogyo Kabushiki
Kaisha (Osaka, JP)
|
Family
ID: |
27565824 |
Appl.
No.: |
07/485,631 |
Filed: |
February 27, 1990 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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233282 |
Aug 17, 1988 |
4923547 |
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Foreign Application Priority Data
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Aug 20, 1987 [JP] |
|
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62-207674 |
Aug 20, 1987 [JP] |
|
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62-207675 |
Sep 16, 1987 [JP] |
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62-231742 |
Sep 16, 1987 [JP] |
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62-231743 |
Dec 15, 1987 [JP] |
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62-316728 |
Dec 22, 1987 [JP] |
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62-326461 |
May 12, 1988 [JP] |
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63-115398 |
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Current U.S.
Class: |
428/174;
428/315.9; 428/319.7; 442/410; 181/294; 428/307.3; 428/310.5;
428/317.7; 428/319.9; 181/291; 428/218; 428/315.7; 428/316.6;
428/408 |
Current CPC
Class: |
D04H
1/558 (20130101); D04H 1/60 (20130101); D04H
1/4209 (20130101); D04H 1/5418 (20200501); Y10T
428/249979 (20150401); Y10T 442/691 (20150401); Y10T
428/24628 (20150115); Y10T 428/249981 (20150401); Y10T
428/24998 (20150401); Y10T 428/249961 (20150401); Y10T
428/249985 (20150401); Y10T 428/249956 (20150401); Y10T
428/30 (20150115); Y10T 428/24992 (20150115); Y10T
428/249992 (20150401); Y10T 428/249993 (20150401) |
Current International
Class: |
D04H
1/00 (20060101); D04H 1/60 (20060101); D04H
1/58 (20060101); B32B 005/26 (); B32B 005/32 ();
E04B 001/88 () |
Field of
Search: |
;428/174,218,285,286,287,288,296,307.3,310.5,311.5,315.7,317.7,408 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Cannon; James C.
Attorney, Agent or Firm: Wenderoth, Lind & Ponack
Parent Case Text
This is a Rule 60 divisional of Ser. No. 07/233,282 filed Aug. 17,
1988, now U.S. Pat. No. 4,923,547.
Claims
What we claim is:
1. A composite molded article made of a nonwoven fibrous mat
wherein inorganic monofilaments having a length of 10 to 200 mm and
a diameter of 2 to 30 micrometers are partially bonded with a
thermoplastic resin binder, many voids being provided throughout
the mat and a large number of fine holes communicating with the
voids in the inside being formed in at least one surface of the
mat, the void ratio being 70 to 98%, the apparent density of the
mat being 0.01 to 0.2 g/cm.sup.3, the binder being distributed more
densely on the surface portion than in the inside of the mat and
the void ratio in the surface portion of the mat being thereby
lower than that in the inside of the mat.
2. The composite modled article of claim 1 wherein inorganic
monofilaments are glass fibers.
3. The composite molded article of claim 1 wherein the binder is a
thermoplastic resin selected from the group consisting of
polyethylene, polypropylene, saturated polyesters, polyamides and
mixtures thereof.
4. The composite molded article of claim 1 wherein a diameter of
most of the fine holes is 2 to 50 micrometers and a density of fine
holes is 1 to 100 holes/cm.sup.2.
Description
This invention relates to a lightweight composite molded article
excellent in rigidity, heat resistance, acoustical properties and
moldability, and specifically to a composite molded article
suitable as an automobile ceiling material, and a process for
producing same.
Corrugated papers and glass fiber reinforced thermosetting resin
sheets have been hitherto used as a substrate of a ceiling material
being one of automobile interior materials. However, corrugated
papers are poor in heat moldability and lack acoustical properties.
Besides, as they are hygroscopic, they absorb moisture and become
heavy, causing sagging. The thermosetting resin sheets are poor in
productivity and heat moldability and also heavy.
Various proposals have been made to eliminate these defects. For
example, Japanese Laid-open Utility Model Application No.
15035/1983 describes an automobile interior material formed by
sequentially laminating a soft synthetic resin foam and a vinyl
chloride leather on one side of a laminate wherein glass fiber
reinforced thermoplastic resin films are laminated on both sides of
a styrene resin foamed sheet. The above interior material has
excellent heat resistance and mechanical strengths, but is
relatively heavy, lacks acoustical properties, and is pricey and
still poor in heat moldability.
Japanese Laid-open Patent Application No. 83832/1985 involves an
automobile ceiling material formed by laminating a foam layer and a
skin on a surface of a substrate wherein thermoplastic resin layers
are laminated on both sides of a glass fiber layer. The above
substrate is thin, and has high mechanical strengths and excellent
heat moldability, but lacks acoustical properties and heat
insulation properties. A foam layer has to be laminated as an
automobile ceiling material, and heat moldability is poor as a
whole.
Besides, in order to improve acoustical properties, an acoustical
material is laminated or penetration holes are formed in a
substrate (Japanese Laid-open Patent Applications No. 11947/1980
& No. 14074/1978 and Japanese Patent Application No.
60944/1982). However, producing steps become complex, costs become
high and tobacco fumes enter the penetration holes to make dirty
the surface.
There has been known a material wherein a synthetic resin foam such
as a polyurethane foam and a decorative skin material such as a
fabric are bonded in this order by an adhesive or by heat on one
side of a nonwoven fabric impregnated with a thermosetting resin
such as a phenolic resin (e.g. Japanese Patent Publication No.
11837/1979 and Japanese Laid-open Patent Application No.
56283/1973). In this type of the automobile ceiling material, the
nonwoven fabric impregnated with the thermosetting resin such as a
phenolic resin requires much time to cure the resin, harmful
substances occur, a void ratio is low, acoustical properties are
not enough, and the weight is relatively heavy.
A glass fiber reinforced resin sheet for obtaining a molded article
by heating and pressing is described as a stampable sheet in
Japanese Patent Publications No. 34292/1983 & No. 13714/1973
(U.S. Pat. No. 3,850,723 & British Patent No. 1,306,145) and
Japanese Laid-open Patent Application No. 161529/ 1987 (European
Patent Application No. 0 223 450). It is stated that the stampable
sheet is a glass fiber reinforced thermoplastic resin sheet, and
when the sheet is heated in stamping, the thickness of the stamping
sheet is increased by resiliency of the glass fibers in the resin.
However, the stamped article is dense and has high specific gravity
and strength and is used as a lawn mower's cover, a panel of a
tractor, an instrument case, an outer frame of a traveler's bag, an
automobile sunroof or a light receiver of an automobile tail
portion, vastly different from the lightweight composite molded
article of this invention excellent in rigidity, heat resistance
and acoustical properties and having a high void ratio.
Japanese Patent Publication No. 34292/1983 includes a process for
producing a glass fiber reinforced thermoplastic resin molded
article which comprises needling a mat made of glass fiber strands,
impregnating it with a thermoplastic resin, pressing the
impregnated mat into a sheet, and stamping the sheet at a flow
temperature of the thermoplastic resin. In the mat used in the
process, glass fibers are bundled in strands which are opened into
monofilaments.
Japanese Patent Publication No. 3714/1973 states a thermoplastic
resin impregnated lofty glass fiber mat. The lofty mat here
referred to is an intermediate product before obtaining a final
molded article by heating and compressing, and not a final product
itself.
Japanese Laid-open Patent Application No. 161529/1987 describes
that a sheet made of a thermoplastic material containing
reinforcing fibers is preheated and expanded, and the expanded
sheet is then molded into an article of a predetermined shape
having portions of different density in a compression mold. It
merely describes that the thermoplastic sheet containing the
reinforcing fibers is expanded in the intermediate step for
obtaining the final molded article.
It is an object of this invention to provide a lightweight
composite molded article excellent in rigidity, heat resistance,
moldability, acoustical properties and flexural strength and
especially suitable as an automobile ceiling material.
Another object of this invention is to provide a process for
producing the composite molded article with high productivity at
low cost.
In one embodiment, this invention provides a composite material
made of a nonwoven fibrous mat wherein inorganic monofilaments
having a length of 10 to 200 mm and a diameter of 2 to 30
micrometers are partially bonded with a thermoplastic resin binder,
many voids being provided throughout the mat and a large number of
fine holes communicating with the voids in the inside being formed
in at least one surface of the mat.
Examples of the inorganic monofilaments used in this invention are
glass fibers, rock wool, ceramic fibers and carbon fibers. Of
these, the glass fibers are preferable. The monofilaments are
obtained by opening glass fiber strands being bundles of many
filaments. The length of the monofilament is preferably 10 to 200
mm from the aspect of moldability of the mat. More preferable is to
contain 70% by weight or more of monofilaments having a length of
50 mm or more. Regarding the diameters of the monofilament, the
lower the diameter the lower the mechanical strengths. As the
diameter is greater, the mat goes heavier and the bulk density
becomes higher. Thus, the diameter is 2 to 30, preferably 5 to 20
micrometers, more preferably 7-13 micrometers.
Examples of the binder to partially bond the inorganic
monofilaments include thermoplastic resins such as polyethylene,
polypropylene, saturated polyesters, polyamides, polystyrene,
polyvinyl butyral and polyurethane. The binder may take any form of
a fiber, powder, solution, suspension, emulsion or film, and is
used in a suitable form depending on a process for producing a
molded article in this invention.
Regarding the ratio of the inorganic monofilaments to the binder,
when the amount of the binder becomes small, a bonded portion
decreases and mechanical strengths of a molded article reduce
Meanwhile, when it becomes large, a void ratio decreases. A
preferable weight ratio is 1:5 to 5:1.
The molded article of this invention is made of a nonwoven fibrous
mat wherein the inorganic monofilaments are partially bonded with a
binder, many voids being provided throughout the mat. When the
density of the molded article increases, it becomes heavy, and when
it decreases, the mechanical strengths decrease. The preferable
density is thus 0.01 to 0.2 g/cm.sup.3. A void ratio as a whole is
preferably 70 to 98%.
A large number of fine holes communicating with the voids in the
inside are formed in at least one side of the molded article. The
diameter of the holes is mostly 2 to 50 micrometers, and the
density of the holes is preferably 1 to 10 holes/cm.sup.2.
It is advisable that the binder to bond the inorganic monofilaments
is more densely distributed on the surface than in the inside of
the molded article, and the void ratio of the surface is lower than
that of the inside. It is preferable that the void ratio of the
surface is 50 to 95% and that of the inside is 85 to 99%.
The thickness of the molded article may properly be determined
depending on the usage. It is usually 4 to 200 mm, and when the
molded article is used as an automobile ceiling material, it is
preferably 4 to 12 mm.
The composite molded article of this invention has the aforesaid
structure. It may be laminated with films, foamed sheets or metal
sheets. Or tackifier or adhesive layers may be laminated on the
surface of the molded article so that the molded article is easy to
adhere to other products. Or closed-cell or open-cell foams such as
a polyethylene foam, a polypropylene foam, a polyurethane foam and
a rubber foam or decorative skin materials such as woven and
nonwoven fabrics and vinyl chloride leathers may be laminated
thereon.
In another embodiment, this invention provides a first process for
producing the aforesaid composite molded article which comprises
forming a nonwoven fibrous mat composed of inorganic monofilaments
having a length of 10 to 200 mm and a diameter of 2 to 30
micrometers and a fibrous and/or powdery thermoplastic resin
binder, heating the mat above the melting point of the
thermoplastic resin binder, compressing the mat at said
temperature, then releasing the compression, recovering the
thickness of the mat to obtain a heat-moldable composite sheet, and
heat-molding the resulting composite sheet.
In the above process, the fibrous or powdery thermoplastic resin
binder is used. Both the fibrous and powdery binders may conjointly
be used. Examples of the thermoplastic resin used are as described
above. Two or more of the thermoplastic resins may conjointly be
used; on this occasion, it is advisable that their melting points
are approximate to each other.
The fibers of the above thermoplastic resin have a length of
preferably 5 to 200 mm, more preferably 20 to 100 mm and a diameter
of preferably 3 to 50 micrometers, more preferably 20 to 40
micrometers from the aspect of excellent moldability in forming a
mat by combining with the inorganic monofilaments.
A diameter of the powder made of the thermoplastic resin is
preferably 50 to 100 mesh when it is added as such. However, when
the powder is added in dispersion or emulsion, the diameter may be
much smaller.
In the process of this invention, a type, a form and a size of the
inorganic monofilaments and a ratio of the inorganic monofilaments
to the thermoplastic resin binder are as noted above.
The mat may be produced by any method. There is, for example, a
method which comprises feeding either fibers or a powder of a
thermoplastic resin and inorganic fiber strands to a carding
machine, and opening the strands into monofilaments to produce a
mat. When the powder of the thermoplastic resin is used, it may be
scattered on the mat as such or in dispersion or emulsion and then
dried after the mat may be formed from the inorganic monofilaments
or if required, from the inorganic monofilaments and the
thermoplastic resin fibers.
To improve mechanical strengths of the mat, the mat may be
needle-punched. It is advisable that the mat is needle-punched at 1
to 50 portions per square centimeter.
The higher the density of the mat, the heavier the mat. The lower
the density of the mat, the lower its mechanical strengths.
Accordingly, the density of the mat is preferably 0.01 to 0.2
g/cm.sup.3, more preferably 0.03 to 0.07 g/cm.sup.3.
In this invention, the mat is heated at a temperature above the
melting point of the thermoplastic resin and then compressed at
said temperature.
By the above heating, the thermoplastic resin is melted to bond the
inorganic monofilaments to each other. It is advisable that the
thermoplastic resin is all melted and the heating is therefore
conducted at a temperature 10.degree. to 70.degree. C. higher than
the melting point of the thermoplastic resin for 1 to 10
minutes.
A heating method may be any method such as a heating method with a
dryer or a radiation heating method with a far infrared heater or
an infrared heater.
After the above heating, the mat is compressed while the
thermoplastic resin is melted. A compression method may be any
method such as compression with a press or compression with
rolls.
A pressure in the press compression is preferably 0.1 to 10
kg/cm.sup.2, more preferably 3 to 4 kg/cm.sup.2. A clearance
between rolls in the roll compression is preferably 1/5 to 1/20,
more preferably 1/8 to 1/15 of the thickness of the mat. When the
thermoplastic resin is cooled and solidified in the compression,
the thickness of the mat is not recovered in the next step. It is
therefore advisable that the press molds and the rolls are both
heated.
By the compression, the molten thermoplastic resin is uniformly
dispersed between the inorganic monofilaments.
The compression is then released and the thickness of the mat is
recovered.
One method for recovering the thickness of the mat is that the
compression-released mat is maintained at a temperature above the
melting point of the binder for a given period of time. The
maintaining time is preferably 10 seconds to 5 minutes, more
preferably 20 seconds to 2 minutes. Another method for recovering
the thickness of the mat is that the compression-released mat is
mechanically pulled while the binder is melted. Such mechanical
pulling is performed such that the mat is laminated in advance of
the compression step with sheets which are melt-adhered to the
molten binder but not to the nonmolten binder and while the binder
is in molten state after releasing the compression, the sheets
bonded to the mat surface by melt adhering with the binder are
pulled outwardly manually or by vacuum suction. Examples of the
sheet which are melt-adhered to the molten binder but not to the
non-molten binder are glass fiber reinforced
polytetrafluoroethylene sheets, sheets whose surface is treated
with polytetrafluoroethylene and polyester sheets whose surface is
subjected to mold release treatment.
The mat with the thickness recovered is cooled to obtain a
heat-moldable composite sheet. When the aforesaid sheets are used
to recover the thickness, the binder becomes non-molten by cooling
and the sheets are therefore easy to peel off from the surface of
the composite sheet after cooling.
The heat-moldable composite sheet can easily be molded by heating
it at a temperature above the melting point of the resin component
and compressing the heated sheet via a press. When in compressing
the sheet via the press the temperature of the press is higher than
the melting point of the resin component, the composite molded
article is adhered to the press and hard to withdraw: the molding
speed is lowered. For this reason, the pressing temperature is
preferably lower than the melting point of the resin component,
more preferably 30.degree. to 100.degree. C. lower than the melting
point of the resin component.
In this manner, the composite molded article of the given shape is
obtained. In the thus obtained composite molded article, the
inorganic monofilaments are bonded to each other at their crosses
with the binder, many voids are provided throughout the mat and a
large number of fine holes communicating with the voids in the
inside are formed in the surface of the mat.
In the first process of this invention, two or more thermoplastic
resins different in melting point can be used as a fibrous
thermoplastic resin binder and the heating temperature of the mat
be a temperature at which the resin of the lower melting point is
melted but the resin of the higher melting point is not.
Consequently, part of the binder remains as such without being
melted, thereby improving thickness recovery properties of the mat
in the thickness recovering step.
In said process, the binder is more densely distributed on the
surface of the mat whereby the void ratio of the surface can be
rendered lower than that in the inside of the mat. A method in
which the binder is more densely distributed on the surface of the
mat is that after formation of the mat, a fibrous or powdery binder
is additionally scattered on the surface of the mat.
In the process, in order to improve the mechanical properties,
thermoplastic films such as polyethylene, polypropylene and
saturated polyesters may be laminated on one or both sides of the
heat-moldable composite sheet before heat-molding, by heat-fusing
or extrusion-laminating. Moreover, for improving acoustical
properties, a large number of holes may be formed in the films.
In still another embodiment, this invention provides a second
process for producing the composite molded article of this
invention which comprises forming a nonwoven fibrous mat from only
inorganic monofilaments having a length of 10 to 200 mm and a
diameter of 2 to 30 micrometers or said inorganic monofilaments and
a fibrous and/or powdery thermoplastic resin binder, laminating one
or more thermoplastic resin films on at least one side of the
nonwoven fibrous mat, heating the laminated sheet at a temperature
above a melting point of at least one of the thermoplastic resin
films, compressing the laminated sheet at said temperature, then
releasing the compression, recovering the thickness of the
laminated sheet to obtain a heat-moldable composite sheet, and
heat-molding the resulting composite sheet.
In the second process, one or more thermoplastic resin films are
laminated on one or both sides of the nonwoven fibrous mat composed
of inorganic monofilaments having a length of 10 to 200 mm and a
diameter of 2 to 30 micrometers. The nonwoven fibrous mat may
contain a fibrous or powdery thermoplastic resin binder.
Usually, the same thermoplastic resin films are laminated on both
sides of the nonwoven fibrous mat. However, thermoplastic resin
films different in melting point may also be laminated on both
sides of the nonwoven fibrous mat. For instance, the melting point
of the thermoplastic resin film being laminated on one side of the
mat can be 10.degree. to 50.degree. C. higher than that of the
thermoplastic resin film being laminated on another side of the
mat. In this case, the laminated sheet is heated at an intermediate
temperature between the melting points of both the resin films. By
the heating, the resin is melted and impregnated in the fibrous mat
on the side on which the resin film of the lower melting point has
been laminated, with the result that a large number of small holes
are formed in said side. Meanwhile, the resin film is retained in
film form on the side on which the the resinous film of the higher
melting point has been laminated.
Thermoplstic resin films approximately identical in melting point
but different in melt index (MI) can be laminated on both sides of
the nonwoven fibrous mat. For instance, a resin film having MI of 2
to 40 g/10 min can be laminated on one side of the mat and a resin
film having MI of 1 to 7 g/10 min on another side thereof. Where
such laminated sheet is heated at a temperature above the melting
points of the thermoplastic resin films, the thermoplastic resin of
higher MI tends to be more impregnated in the fibrous mat than the
thermoplastic resin of lower MI because of difference in
flowability of the resins laminated on both sides. Accordingly, by
properly selecting the heating and compressing conditions, the
thermoplastic resin can be impregnated in one side of the mat to
form a large number of small holes in said side and the
thermoplastic resin be maintained in film state on another
side.
It is possible that two or more thermoplastic resin films are
laminated on one side of the nonwoven fibrous mat and MI's of the
two or more thermoplastic resin films are increased sequentially
from the outer layer to the innner layer. When the resulting
laminated sheet is heated and compressed, the resin film laminated
on the innermost layer is impregnated in the inside of the mat
because of the highest MI. On the other hand, the resin film
laminated on the outermost layer is retained in the vicinity of the
surface of the mat because of the lowest MI. Consequently, the
resin is distributed more densely on the surface portion than on
the central portion of the mat.
It is also possible that two or more thermo-plastic resins are
laminated on one side of the nonwoven fibrous mat and the melting
points of the two or more resin films are lowered sequentially from
the outer layer to the inner layer. Where the resulting laminated
sheet is heated and compressed, the resin film laminated on the
innermost layer is impregnated in the inside of the mat, while the
resin film laminated on the outermost layer is maintained on the
surface of the mat. Consequently, the resin is distributed more
densely on the surface portion than on the central portion of the
mat.
Besides, the molten resin can be impregnated more densely in the
surface portion than in the inside of the mat by controlling the
pressure and time of the compression step and releasing the
compression before the molten resin of the thermoplastic resin film
is uniformly impregnated up to the inside.
Examples of the thermoplastic resin film being laminated on the
nonwoven fibrous mat are films of thermoplastic resins such as
polyethylene, polypropylene, polystyrene, saturated polyesters,
polyurethane, polyvinyl butyral and polyvinyl chloride. These resin
films can be used singly or in combination. As stated above, when
the fibrous or powdery thermoplastic resin binder is used in the
fibrous mat, a binder having a melting point which is the same as
or lower than the melting point of the resin film is preferable. In
order to improve the bulk density of the mat, a binder having a
higher melting point than that of the resin film is available.
As the thickness of the thermoplastic resin film is higher, it
becomes heavier. Meanwhile, as the thickness of the thermoplastic
resin film is lower, the mechanical strengths decrease. The
preferable thickness is therefore 10 to 300 micrometers. Where the
fibrous or powdery resin binder is conjointly used, the inorganic
monofilaments are bonded with said fibers or powder, making it
possible to thin the thermoplastic resin film.
The thermoplastic resin film may be laminated by any optional
method such as heat-fusing or extrusion-laminating.
The laminated sheet composed of the nonwoven fibrous mat and the
thermoplastic resin films is heated at a temperature above the
melting point of at least one thermoplastic resin film and
compressed at said temperature, the compression is then released
and the thickness is recovered to obtain the heat-moldable
composite sheet, followed by heat-molding it. The steps of
compressing the laminated sheet, releasing the compression,
recovering the thickness and heat-molding the composite sheet are
approximately the same as those in the first process.
During the heating and compressing steps, the thermoplastic resin
films are melted and impregnated in the inorganic fibrous mat.
Thus, the inorganic monofilaments are bonded to each other at their
crosses by the resin component, many voids are provided throughout
the mat and a large number of fine holes communicating with the
voids in the inside are formed in the surface of the mat by melting
and impregnating the resin films, thereby improving acoustical
properties of the molded article. By the way, the large number of
the fine holes are formed in the heat-moldable composite sheet, and
also in heat-molding the resin on the surface is melted to form
fine holes. For further increasing the number of such fine holes,
holes may be formed in the surface of the composite molded article
by e.g. a needle.
In the first and second processes of this invention, it is possible
that a closed-cell thermoplastic resin foam having preferably many
penetration holes and a decorative skin material preferably having
air-permeability are sequentially laminated on one side of the mat
or heat-moldable sheet before the heat-molding step, and the
resulting laminate is then heat molded. The thus obtained composite
molded article is useful especially as an automobile ceiling
material.
Examples of the thermoplastic resin foam are foams of polyolefin
resins such as polyethylene and polypropylene, an ethylene/vinyl
acetate copolymer foam and a polyvinyl chloride resin foam.
Especially, the polyolefin resin foam containing the ethylene/vinyl
acetate copolymer is preferable owing to good adhesion.
Such foam has preferably compression strength (measured according
to JIS K 6767) of 0.1 to 2.0 kg/cm.sup.2. When the compression
strength decreases, pressing is not thoroughly conducted and
adhesion strength decreases. Meanwhile, when the compression
strength increases, no sufficient cushioning properties are
obtained.
It is preferable that the above foam is provided with many
penetration holes and the penetration hole has a diameter of 0.1 to
5.0 mm and an opening ratio of 0.5 to 30%. Where the diameter is
smaller than 0.1 mm and the opening ratio is lower than 0.5%,
acoustical properties decrease. On the other hand, where the
diameter is larger than 5.0 mm and the opening ratio is higher than
30%, the uniform smoothness of the surface is lost.
When the foam is thin, the cushioning properties are insufficient.
When it is thick, the delicate moldability of the surface is poor.
The thickness of the foam is therefore preferably 0.5 to 5.0 mm,
more preferably 1.0 to 3.0 mm.
The decorative skin material being integrally laminated on the foam
surface has preferably air-permeability, and woven and nonwoven
fabrics are generally available as the air-permeable decorative
skin material.
The above closed-cell foam and the decorative skin material are
laminated sequentially on one side of the nonwoven fibrous mat or
laminated sheet, and they are bonded to each other and
integrated.
On this occasion, an adhesive such as a hot-melt adhesive may be
coated on the foam and the decorative skin material to such extent
that the air-permeability is not impaired, followed by sequentially
laminating them. Or the foam and the decorative skin material may
be bonded in advance via heat-bonding or with an adhesive such as a
hot melt adhesive to such extent that the air-permeability is not
so much impaired. An open-cell soft polyurethan foam may be
interleaved between the mat or the heat-moldable composite sheet
and the decorative skin material.
Since the composite molded article of this invention is formed of
the nonwoven fibrous mat wherein the inorganic monofilaments are
partially bonded with the thermoplastic resin binder, sufficient
strength and heat resistance and higher void ratio than in the
conventional molded articles are achieved and high acoustical
properties are therefore obtained.
The composite molded article of this invention is preferably
produced by a process which comprises once heating and compressing
the mat wherein the inorganic monofilaments are partially bonded
with a resinous, powdery and/or film-like thermoplastic resin, then
recovering the thickness of the mat, and conducting heat-molding.
The high strength is provided by bonding the inorganic
monofilaments to the binder resin upon heating and compressing, and
the sufficient void ratio is attained by the subsequent thickness
recovering. In addition, since the binder resin is impregnated from
the surface into the inside of the inorganic fibrous mat and
subjected to heat-molding, the large number of the fine holes
communicating with the voids in the inside are formed in the
surface of the mat to provide the high acoustical properties.
The nonwoven fibrous heat-moldable composite sheet obtained via the
heating, compressing and thickness recovering steps has good
heat-moldability and is easily molded into a desirable shape by a
simple processing means such as a press; a molded article having a
curvature corresponding to a curvature of a mold can be
afforded.
The following Examples and Comparative Examples illustrate this
invention more specifically.
EXAMPLE 1
Glass fiber chopped strands (length of 50 mm, monofilament diameter
of 10 micrometers) and high-density polyethylene fibers (diameter
of 30 micrometers, length of 50 mm, melting point of 135.degree.
C., MI of 5) were fed at a weight ratio of 4:1 to a carding machine
where the glass fiber chopped strands were opened into
monofilaments. Both were then combined into a mat-like material.
The mat-like material was needle-punched at 30 portions per square
centimeter to obtain a nonwoven fibrous mat having a thickness of
10 mm.
High-density polyethylene sheets (thickness of 100 micrometers,
melting point of 135.degree. C., MI of 5) were laminated on both
sides of the nonwoven fibrous mat. Glass fiber reinforced
polytetrafluoroethylene sheets (thickness of 150 micrometers) were
laminated on both sides of the mat. The laminate was heated at
200.degree. C. for 3 minutes and then compressed into a sheet with
a press of 200.degree. C. at a pressure of 10 kg/cm.sup.2. In this
case, the thickness of the laminate was 0.6 mm. The compression
time was 20 seconds. After releasing the compression, the
polytetrafluoroethylene sheets on both sides were sucked in vacuo
while maintaining the temperature at 200.degree. C., and the
thickness of the laminated sheet was recovered up to 9 mm.
Subsequently, the laminated sheet was cooled with air for 3
minutes, and the polytetrafluoroethylene sheets were then peeled
off to afford a heat-moldable composite sheet.
The resulting composite sheet was heated in an oven of 200.degree.
C. for 2 minutes and compressed with a mold of 30.degree. C. for 1
minute at a compression force of 1 kg/cm.sup.2 to obtain a molded
article. The mold had the thinnest portion of 3 mm and the thickest
portion of 8 mm. A curvature radius of a recessed portion in the
mold was 5 mm. The resulting molded article was a tray-like molded
article 1400 mm long and 1150 mm wide.
An average void ratio of the molded article was 90%, a void ratio
of the surface portion 70%, and a void ratio of the central portion
95% respectively. A hole density of the surface was 50
holes/cm.sup.2, the hole diameter was 2 to 100 micrometers, and
most of the holes had a diameter of 30 to 40 micrometers.
The resulting molded article was subjected to a flexural test
according to JIS K 7221 (the test piece had a thickness of 5 mm, a
width of 50 mm and a length of 150 mm) and measured for heat
moldability (a curvature radius of a portion in the molded article
corresponding to the curvature radius, 5 mm of the recessed portion
in the mold) and acoustical properties by a vertical incidence
method according to JIS A 1405. The results are tabulated
below.
______________________________________ Maximum flexural load (kg)
1.7-2.0 Flexural strength (kg/cm.sup.2) 35-40 Flexural modulus
(kg/cm.sup.2) 3000-4000 Heat-moldability 5.5 (curvature radius: mm)
Acoustical properties (%) 0.80 KHz 67 1.00 KHz 81 1.25 KHz 81 1.60
KHz 80 2.00 KHz 78 ______________________________________
EXAMPLE 2
Glass fiber chopped strands (length of 50 to 100 mm, monofilament
diameter of 10 micrometers) and polyethylene fibers (length of 51
mm, diameter of 30 micrometers, melting point of 135.degree. C., MI
of 20) were fed at a weight ratio of 1:2 to a carding machine where
the glass fiber chopped strands were opened into monofilaments.
Both were combined into a mat-like material. The mat-like material
was needle-punched at 20 portions per square centimeter to obtain a
mat having a thickness of 10 mm and a weight of 800 g/m.sup.2.
The resulting mat was fed to a hot-air dryer where it was dried at
200.degree. C. for 3 minutes. Subsequently, the heated mat was
compressed through rolls with a clearance between rolls of 1 mm.
The compressed mat was fed again to the hot-air dryer where it was
maintained at 200.degree. C. for 3 minutes. There resulted a
heat-moldable composite sheet having a thickness of 8 mm.
Both sides of the resulting composite sheet were heated with a
infrared heater of 200.degree. C. for 3 minutes and fed to a mold
having a depth of 10 mm, a clearance between molds of 5 mm and a
curvature radius of a recessed portion of 5 mm (mold temperature of
25.degree. C.) where the composite sheet was pressed at a pressure
of 0.05 to 1.0 kg/cm.sup.2 for 2 minutes to obtain a tray-like
molded article.
The resulting molded article was measured for flexural strength and
flexural modulus (according to JIS K 7221), heat moldability (a
curvature radius of a portion in the molded article corresponding
to the curvature radius, 5 mm of the recessed portion in the mold),
dimensional stability (shrinkage after heating with a hot-air dryer
of 90.degree. C. for 100 hours) and acoustical properties by a
vertical incidence method according to JIS A 1405 (1 KHz). The
results are shown in Table 1.
EXAMPLE 3
Glass fiber chopped strands (length of 50 to 100 mm monofilament
diameter of 10 micrometers) and polyethylene fibers (length of 51
mm, diameter of 30 micrometers, melting point of 135.degree. C., MI
of 20) were fed at a weight ratio of 1:1 to a carding machine where
the glass fiber chopped strands were opened into monofilaments.
Both were combined into a mat-like material. The mat-like material
was needle-punched at 20 portions per square centimeter to obtain a
mat having a thickness of 10 mm and a weight of 700 g/m.sup.2.
In the same way as in Example 2, the resulting mat was heated,
compressed through the rolls spaced apart at an interval of 1 mm
and further heated, followed by recovering the thickness. There was
obtained a mat having a thickness of 7 mm. Polyethylene (melting
point of 135.degree. C., MI of 5) was extrusion-laminated onto both
sides of the resulting mat to provide a heat-moldable composite
sheet. Each of the polyethylene layers was 50 g/m.sup.2.
In the same way as in Example 2, a molded article was produced from
the resulting composite sheet and then measured for various
properties. The results are shown in Table 1.
COMPARATIVE EXAMPLE 1
The mat obtained in Example 3 was fed to a hot-air dryer where it
was heated at 200.degree. C. for 3 minutes. The heated mat was then
compressed via rolls spaced apart at an interval of 1 mm, and left
to cool. There was obtained a mat having a thickness of 2.5 mm.
Polyethylene (melting point of 135.degree. C., MI of 5) was
extrusion-laminated onto both sides of the resulting mat to provide
a heat-moldable composite sheet. Each of the polyethylene layers
was 50 g/m.sup.2.
A molded article was obtained from the resulting composite sheet as
in Example 2 except that a clearance between molds was 2 mm, and
measured for various properties as in Example 2. The results are
shown in Table 1.
EXAMPLE 4
Glass fiber chopped strands (length of 50 to 100 mm, monofilament
diameter of 10 micrometers) and a polyethylene powder (diameter of
10.0 to 200 micrometers, melting point of 135.degree. C., MI of 5)
were fed at a weight ratio of 1:1 to a carding machine where the
glass fiber chopped strands were opened into filaments. Both were
combined into a mat-like material. The mat-like material was
needle-punched at 20 portions per square centimeter to obtain a mat
having a thickness of 7 mm and a weight of 700 g/m.sup.2.
In the same way as in Example 3, the resulting mat was heated,
compressed via rolls, and then heated to obtain a mat having a
thickness of 6 mm. Polyethylene was extrusion-laminated on both
sides of the mat to afford a heat-moldable composite sheet.
In the same way as in Example 2, a molded article was obtained from
the resulting composite sheet and measured for various properties.
The results are shown in Table 1.
EXAMPLE 5
Glass fiber chopped strands (length of 40 to 200 mm, monofilament
diameter of 9 to 13 micrometers) and polyethylene fibers (length of
51 mm, diameter of 30 micrometers, melting point of 135.degree. C.,
MI of 20) were fed at a weight ratio of 1:2 to a carding machine
where the glass fiber chopped strands were opened into
monofilaments. Both were combined into a mat-like material. The
mat-like material was needle-punched at 20 portions per square
centimeter to obtain a mat having a thickness of 10 mm and a weight
of 800 g/m.sup.2. Glass fiber reinforced polytetrafluoroethylene
sheets (thickness of 150 micrometers) were laminated on both sides
of the mat, heated at 200.degree. C. for 3 minutes and compressed
with rolls heated at 200.degree. C. and spaced apart at an interval
of 1.3 mm. Subsequently, the compression was released. While
maintaining the temperature at 200.degree. C., the glass fiber
reinforced polytetrafluoroethylene sheets were sucked in vacuo from
both sides at a rate of 0.5 mm/second to recover the thickness of
the mat up to 9 mm. Subsequently, the mat was cooled with air for 3
minutes and the polytetrafluoroethylene sheets were peeled off to
obtain a heat-moldable composite sheet.
The resulting composite material was heated in an oven of
200.degree. C. for 2 minutes and then compressed with a mold of
30.degree. C. at a compression force of 1 kg/cm.sup.2 for 1 minute
to provide a molded article. The mold had the thinnest portion of
3.0 mm and the thickest portion of 8 0 mm. A curvature radius of a
recessed portion in the mold was 5 mm. The molded article was 1400
mm long and 1150 mm wide.
The resulting molded article was fed to a hot-air dryer held at
95.degree. C. where it was dried for 24 hours while holding all
sides thereof. At this time, a heat distortion resistance (amount
of sagging) was measured. Further, a flexural strength was measured
according to JIS K 7221 (the test piece had a thickness of 6 mm, a
width of 50 mm and a length of 150 mm). Still further, acoustical
properties at 1500 Hz was measured by a vertical incidence method
according to JIS A 1405. A heat moldability of the composite
material was evaluated by measuring a curvature radius of a portion
in the molded article corresponding to the curvature radius, 5 mm
of the recessed portion in the mold. The results are shown in Table
2.
EXAMPLE 6
Glass fiber chopped strands (length of 50 to 100 mm, monofilament
diameter of 10 micrometers) and polyethylene fibers (length of 51
mm, diameter of 30 micrometers, melting point of 135.degree. C., MI
of 20) were fed at a weight ratio of 3:1 to a carding machine where
the strands were opened into monofilaments. Both were combined into
a mat-like material The mat-like material was needle-punched at 20
portions per square centimeter. Subsequently, polyethylene films
(melting point of 135.degree. C., MI of 5, weight of 100 g/m.sup.2)
were laminated on both sides of the mat to form a laminated sheet
having a thickness of 10 mm and a weight of 800 g/m.sup.2.
The resulting laminated sheet was fed to a not-air dryer where it
was heated at 200.degree. C. for 3 minutes. Thereafter, the sheet
was compressed via rolls spaced apart at an interval of 1 mm, and
fed again to the hot-air dryer where it was maintained at
200.degree. C. for 3 minutes. There was obtained a heat-moldable
composite sheet having a thickness of 7 mm.
Both sides of the resulting composite sheet were heated with an
infrared heater of 200.degree. C. for 3 minutes. The sheet was fed
to a mold having a depth of 10 mm, a clearance between molds of 5
mm and a curvature radius of a recessed portion of 5 mm (mold
temperature of 25.degree. C.) where it was pressed at a pressure of
0.05 to 1.0 kg/cm.sup.2 for 2 minutes. There resulted a tray-like
molded article.
The resulting molded article was measured for flexural strength,
flexural modulus, moldability, dimensional stability and acoustical
properties in the same way as in Example 2. The results are shown
in Table 1.
EXAMPLE 7
Glass fiber chopped strands (length of 50 to 100 mm, monofilament
diameter of 10 micrometers) and a polyethylene powder (diameter of
100 to 200 micrometers, melting point of 135.degree. C., MI of 5)
were fed at a weight ratio of 2:1 to a carding machine where the
strands were opened into monofilaments. Both were combined into a
mat-like material. The mat-like material was needle-punched at 20
portions per square centimeter and then polyethylene films (melting
point of 135.degree. C., MI of 5, weight of 100 g/m.sup.2) were
laminated on both sides of the mat-like material to obtain a
laminated sheet having a thickness of 10 mm and a weight of 800
g/m.sup.2.
In the same way as in Example 6, the resulting laminated sheet was
heated, compressed via rolls and then heated to afford a
heat-moldable composite sheet having a thickness of 7 mm. In the
same way as in Example 6, a molded article was produced from the
composite sheet and measured for various properties. The results
are shown in Table 1.
EXAMPLE 8
Glass fiber chopped strands (length of 50 to 100 mm, monofilament
diameter of 10 micrometers) were fed to a carding machine where the
strands were opened into monofilaments. They were combined into a
mat-like material. The mat-like material was needle-punched at 20
portions per square centimeter. Subsequently, polyethylene films
(melting point of 135.degree. C., MI of 5, weight of 150 g/m.sup.2)
were laminated on both sides of the mat-like material to obtain a
laminated sheet having a thickness of 10 mm and a weight of 800
g/m.sup.2.
In the same way as in Example 6, the resulting laminated sheet was
heated, compressed via rolls and then heated to afford a
heat-moldable composite sheet having a thickness of 7 mm.
In the same way as in Example 6, a molded article was obtained from
the thus obtained composite sheet and measured for various
properties. The results are shown in Table 1.
COMPARATIVE EXAMPLE 2
The laminated sheet obtained in Example 6 was fed to a hot-air
dryer where it was heated at 200.degree. C. for 3 minutes. The
resulting sheet was then compressed via rolls spaced apart at an
interval of 1 mm and allowed to cool. There was obtained a
composite sheet having a thickness of 2.5 mm.
A molded article was obtained from the resulting composite sheet as
in Example 6 except that an interval between molds was 2 mm, and
measured for various properties as in Example 6. The results are
shown in Table 1.
EXAMPLE 9
Glass fiber chopped strands (length of 40 to 200 mm, monofilament
diameter of 9 to 13 micrometers) were fed to a carding machine
where said strands were opened into monofilaments. They were
combined into a mat-like material. The mat-like material was
needle-punched at 20 portions per square centimeter to obtain a mat
having a thickness of 10 mm and a weight of 600 g/m.sup.2.
Polyethylene sheets (thickness of 10 micrometers, weight 100
g/m.sup.2, melting point of 135.degree. C., MI of 5) were laminated
on both sides of the mat to afford a laminated sheet. Glass fiber
reinforced polytetrafluoroethylene sheets (thickness of 150
micrometers) were laminated on both sides of the resulting
laminated sheet, heated at 200.degree. C. for 3 minutes and
compressed at a rate of 10 cm/sec via rolls heated at 200.degree.
C. and spaced apart at an interval of 1.3 mm. Thereafter the
compression was released, and while keeping the temperature at
200.degree. C., the glass fiber reinforced polytetrafluoroethylene
sheets were sucked in vacuo from both sides at a rate of 0.5 mm/sec
to recover the thickness of the laminated sheet up to 8 mm. The
laminated sheet was then cooled with air for 3 minutes, followed by
peeling off the tetrafluoroethylene sheets. There resulted a
heat-moldable composite sheet.
The resulting composite sheet was heated in an oven of 200.degree.
C. for 2 minutes and then compressed with a mold of 30.degree. C.
at a compression force of 1 kg/cm.sup.2. The mold had the thinnest
portion of 3.0 mm and the thickest portion of 8.0 mm. A curvature
radius of the recessed portion in the mold was 5 mm. The molded
article was 1400 mm long and 1150 mm wide.
The molded article was measured for various properties in the same
way as in Example 5. The results are shown in Table 2.
EXAMPLE 10
Glass fiber chopped strands (length of 40 to 200 mm, monofilament
diameter of 9 to 13 micrometers and polyethylene fibers (length of
50 mm, diameter of 30 micrometers, melting point of 135.degree. C.,
MI of 20) were fed at a weight ratio of 4:1 to a carding machine
where the glass fiber strands were opened into monofilaments. Both
were combined into a mat-like material. The mat-like material was
needle-punched at 20 portions per square centimeter to obtain a mat
having a thickness of 10 mm and a weight of 600 g/m.sup.2.
Polyethylene sheets (thickness of 100 micrometers, weight of 100
g/m.sup.2, melting point of 135.degree. C., MI of 5) were laminated
on both sides of the mat to afford a laminated sheet. Glass fiber
reinforced polytetrafluoroethylene sheets (thickness of 150
micrometers) were laminated on both sides of the laminated sheet,
heated at 200.degree. C. for 3 minutes and compressed with a flat
press at a pressure of 10 kg/cm.sup.2 for 30 seconds. After
releasing the compression, the polytetrafluoroethylene sheets on
both sides were sucked in vacuo while keeping the temperature at
200.degree. C. to recover the thickness of the laminated sheet up
to 9 mm. Thereafter, the laminated sheet was cooled with air for 3
minutes and the polytetrafluoroethylene sheets were then peeled off
to obtain a heat-moldable composite sheet.
The resulting composite sheet was heated in an oven of 200.degree.
C. for 2 minutes and then compressed with a mold of 30.degree. C.
at a compression force of 1 kg/cm.sup.2 for 1 minute to provide a
molded article. The mold had the thinnest portion of 3 mm and the
thickest portion of 8 mm. A curvature radius of a recessed portion
in the mold was 5 mm. The molded article was 1400 mm long and 1150
mm wide.
The molded article was measured for various properties as in
Example 5. The results are shown in Table 2.
TABLE 1
__________________________________________________________________________
Flexural Flexural Moldability Dimensional Acoustical strength
modulus (curvature stability properties (kg/cm.sup.2) (kg/cm.sup.2)
radius) (mm) (%) (1 KHz) (%)
__________________________________________________________________________
Example 2 15-20 3000-4000 5.5 0.06 78 3 20-30 3500-4500 5.5 0.07 65
4 15-25 3500-4000 5.5 0.08 62 6 25-30 3500-4500 5.5 0.07 65 7 15-25
3000-3500 5.5 0.08 62 8 20-30 3500-4500 5.5 0.06 67 Comparative 1
30-40 6000-8000 8.0 0.08 38 Example 2 30-40 6000-8000 8.0 0.08 37
__________________________________________________________________________
TABLE 2 ______________________________________ Heat Heat distortion
Flexural Acoustical moldability resistance strength properties
(curvature Example (mm) (kg/cm.sup.2) (1.5 KHz) (%) radius) (mm)
______________________________________ 5 1.7 20.1 90 5.4 9 1.5 18.9
92 5.5 10 1.3 19.1 91 5.2
______________________________________
EXAMPLE 11
Sixty-five percent by weight of glass fiber strands (length of 40
to 100 mm, monofilament diameter of 9 to 13 micrometers) and 35% by
weight of high-density polyethylene fibers (length of 40 to 100 mm,
diameter of 6 denier, melting point of 135.degree. C., MI of 20)
were fed to a carding machine where the strands were opened into
monofilaments. Both were combined into a mat-like material. The
mat-like material was needle-punched at 15 portions per square
centimeter to obtain a nonwoven fibrous mat having a thickness of
10 mm and a weight of 500 g/m.sup.2.
Low-density polyethylene films (thickness of 150 micrometers,
melting point of 107.degree. C., MI of 5) were laminated on both
sides of the nonwoven fibrous mat. The laminate was heated and
compressed with a press of 120.degree. C. at a pressure of 1
kg/cm.sup.2 for 10 seconds to decrease the thickness. Thereafter,
the compression was released and the laminate was held at
120.degree. C. for 20 seconds to increase the thickness. There
resulted a heat-moldable composite sheet having a thickness of 8.3
mm.
The above composite sheet was heated from both sides by an infrared
heater until the surface temperature reached 170.degree. C., and
immediately placed into a mold of 30.degree. C. where it was
compression-molded into a final shape at a pressure of 1
kg/cm.sup.2 for 1 minute. The mold had the thinnest portion of 2.5
mm and the thickest portion of 5.0 mm. A curvature radius of a
recessed portion in the mold was 5 mm. A heat moldability was
evaluated by measuring whether the molded article was shaped to
correspond to the recessed portion in the mold.
The above molded article was measured for heat distortion
resistance (amount of sagging) after heating it in a hot-air oven
of 95.degree. C. for 24 hours while holding all sides thereof.
Further, from the above molded article, a test piece having a
thickness of 5 mm, a width of 50 mm and a length of 150 mm was cut
out and measured for flexural strength and flexural modulus
according to JIS K 7221. Still further, from the molded article, a
test piece having a thickness of 8 mm and a diameter of 90 mm was
cut out and measured for acoustical properties at 1000 Hz by a
vertical incidence method according to JIS A 1405. The results are
shown in Table 3.
EXAMPLE 12
A heat-moldable composite sheet having a thickness of 8.7 mm was
obtained in the same way as in Example 11 except that the
high-density polyethylene fibers were replaced with polyester
fibers (melting point of 160.degree. C.).
A molded article was produced from the composite sheet as in
Example 11 except that the surface temperature in molding the
composite sheet into a final shape was changed into 200.degree. C.,
and measured for various properties as in Example 11. The results
are shown in Table 3.
TABLE 3 ______________________________________ Ex- Flexural
Flexural Heat distor- Acoustical Heat am- strength modulus tion
resis- properties mold- ple (kg/cm.sup.2) (kg/cm.sup.2) tance (mm)
(%) (1 KHz) ability ______________________________________ 11 15-20
3600-3900 1.3 71 5.4 12 15-20 3500-3700 2.0 68 5.5
______________________________________
EXAMPLE 13
Glass fiber chopped strands (length of 50 to 100 mm, monofilament
diameter of 10 micrometers) and high-density polyethylene fibers
(length of 51 mm, diameter of 30 micrometers, melting point of
135.degree. C., MI of 20) were fed at a weight ratio of 3:1 to a
carding machine where the strands were opened into monofilaments.
Both were combined into a mat-like material. The mat-like material
was needle-punched at 20 portions per square centimeter to obtain a
mat.
High-density polyethylene films (melting point of 135.degree. C.,
weight of 100 g/m.sup.2, MI of 5) were laminated on both sides of
the mat to form a laminated sheet having a thickness of 10 mm and a
weight of 800 g/m.sup.2. After heated in an oven of 200.degree. C.
for 3 minutes, the laminated sheet was compressed through a pair of
rolls spaced apart at an interval of 1 mm. The compression was then
released and the thickness was recovered while the laminated sheet
was held again in the oven of 200.degree. C. for 3 minutes. There
resulted a heat-moldable composite sheet having a thickness of 7
mm.
In the heat-moldable composite sheet, the glass fibers were
partially bonded with the molten high-density polyethylene fibers
and films as binders, and many voids were formed throughout the
sheet; air-permeability was therefore provided.
The heat-moldable composite sheet was heated at both sides with an
infrared heater of 200.degree. C. for 3 minutes. On one side of the
heated heat-moldable composite sheet were rapidly laminated a
closed-cell, crosslinked, low-density polyethylene foam (thickness
of 2 mm, compression strength of 0.3 kg/cm.sup.2) provided with a
large number of penetration holes each having a diameter of 1.5 mm
at an opening ratio of 5.0% and a decorative skin material made of
an air-permeable nonwoven fabric having a thickness of 1 mm in this
order.
By the way, the foam and the nonwoven fabric were integrally bonded
in advance to each other with a chloroprene-type hot melt adhesive
so as not to impair air-permeability of the foam and the nonwoven
fabric.
The above laminate was placed into a press (depth of 10 mm,
clearance between molds of 8 mm, curvature radius of a recessed
portion of 5 mm) held at 25.degree. C. where it was pressed at a
pressure of 0.2 kg/cm.sup.2 for 25 seconds. There was obtained an
automobile ceiling material.
The resulting automobile ceiling material had air-permeability; it
was measured for heat moldability, heat resistance, flexural
strength, acoustical properties and bonding strength. The results
are shown in Table 4.
The heat moldability was evaluated by measuring a curvature radius
of a portion in the ceiling material corresponding to the curvature
radius, 5 mm of the recessed portion in the mold. The dimensional
stability was evaluated by measuring shrinkage after the ceiling
material was heated in an oven of 90.degree. C. for 100 hours. The
flexural strength was evaluated by cutting out a test piece having
a thickness of 8 mm, a width of 100 mm and a length of 150 mm from
the ceiling material and measuring it according to JIS K 7221. The
acoustical properties were evaluated by cutting out a test piece
having a thickness of 8 mm and a diameter of 90 mm from the ceiling
material and measuring it through a vertical incidence method (1.5
KHz) according to JIS A 1405. The bonding strength was evaluated by
peeling off the heat-moldable composite sheet and the foam at one
end of the test piece 25 mm in width and 150 mm in length and
conducting a 180 .degree. peel strength test (pulling rate of 300
mm/min).
EXAMPLE 14
Example 13 was repeated except that a crosslinked, low-density
polyethylene foam having a compression strength of 1.0 kg/cm.sup.2
was used and an open-cell, soft polyurethane foam having a
compression strength of 0.03 kg/cm.sup.2 and a thickness of 1 mm
was interposed between the polyethylene foam and the decorative
skin material and they were integrally bonded with an adhesive. The
results are shown in Table 4.
TABLE 4
__________________________________________________________________________
Heat Dimensional Flexural Acoustical Adhesive moldability stability
strength properties strength Example (mm) (%) (kg/cm.sup.2) (1.5
KHz) (%) (kg/25 mm width)
__________________________________________________________________________
13 5.7 0.07 17 72 2.0 (The polyethylene foam was destroyed.) 14 5.8
0.09 18 71 5.7 (Part of the poly- ethylene foam was destroyed.)
__________________________________________________________________________
EXAMPLE 15
Glass fiber chopped strands (length of 40 to 200 mm, monofilament
diameter of 9 to 13 micrometers) and polyethylene fibers (length of
50 mm, diameter of 30 micrometers, melting point of 135.degree. C.,
MI of 5) were fed at a weight ratio of 4:1 to a carding machine
where the strands were opened into monofilaments. Both were
combined into a mat-like material. The mat-like material was
needle-punched at 20 portions per square centimeter to obtain a mat
having a thickness of 10 mm and a weight of 500 g/m.sup.2
Polyethylene sheets (thicknesses of 100 micrometers and 200
micrometers, melting point of 135.degree. C., MI of 5) were
laminated on both sides of the mat to afford a laminated sheet. On
both sides of the laminated sheet were laminated glass fiber
reinforced polytetrafluoroethylene sheets (thickness of 150
micrometers). The laminate was heated while compressing it with a
press comprising a lower mold of 200.degree. C. (on the side of the
200-micrometer polyethylene sheet) and an upper mold of 50.degree.
C. (on the side of the 100-micrometer polyethylene sheet) at a
pressure of 0.2 kg/cm.sup.2 for 3 minutes. Detection with a heat
label revealed that the polyethylene sheet portion on the lower
mold side reached 200.degree. C. and the polyethylene sheet portion
on the upper mold side reached 115.degree. C. It was found that the
polyethylene sheet portion on the lower mold side was melted.
Subsequently, the pressure of the press was elevated to 10
kg/cm.sup.2 and the compression was conducted for 20 seconds. The
polytetrafluoroethylene sheets on both sides were then sucked in
vacuo at the above temperatures to recover the thickness of the
laminated sheet up to 9 mm. Thereafter, the laminated sheet was
cooled with air for 3 minutes, followed by peeling off the
polytetrafluoroethylene sheets. There resulted a heat-moldable
composite sheet. In the composite sheet, polyethylene was
impregnated in the mat on the lower mold side and the polyethylene
sheet remained in film form on the upper mold side.
The resulting composite sheet was heated to 200.degree. C. on the
lower mold side and to 120.degree. C. on the upper mold side
through an infrared heater. The sheet was compressed with a mold of
30.degree. C. at a compression force of 1 kg/cm.sup.2 for 1 minute
to afford a molded article. The mold had the thinnest portion of
3.0 mm and the thickest portion of 8.0 mm. A curvature radius of a
recessed portion in the mold was 5 mm. The molded article was 1400
mm long and 1150 mm wide. A large number of small holes were formed
in the surface of the molded article on the upper mold side.
The resulting molded article was fed to a hot-air dryer set at
95.degree. C. where it was heated for 24 hours while holding all
sides thereof. At this time, a heat distortion resistance (amount
of sagging) was measured. The flexural strength and the flexural
modulus were evaluated by measuring a test piece having a thickness
of 6 mm, a width of 50 mm and a length of 150 mm according to JIS K
7221. Acoustical properties at 1000 Hz was measured by a vertical
incidence method according to JIS A 1405. An air-permeability was
also measured. The results are shown in Table 5.
EXAMPLE 16
Glass fiber chopped strands (length of 40 to 200 mm, monofilament
diameter of 9 to 13 micrometers, melting point of 135.degree. C.,
MI of 5) and polyethylene fibers (length of 50 micrometers,
diameter of 30 micrometers) were fed at a weight ratio of 4:1 to a
carding machine where the strands were opened into filaments. Both
were combined into a mat-like material. The mat-like material was
needle-punched at 20 positions per square centimeter to obtain a
mat having a thickness of 10 mm and a weight of 500 g/m.sup.2. On
both sides of the mat were laminated a polyethylene sheet
(thickness of 200 micrometers, weight of about 200 g/m.sup.2,
melting point of 135, MI of 5) and a polypropylene sheet (thickness
of 100 micrometers, weight of about 100 g/m.sup.2, melting point of
165.degree. C., MI of 1) to afford a laminated sheet. Glass fiber
reinforced polytetrafluoroethylene sheets (thickness of 150
micrometers) were laminated on both sides of the laminated sheet,
heated at 160.degree. C. for 3 minutes and compressed with a flat
press at a pressure of 10 kg/cm.sup.2 for 20 seconds. The
compression was released, and while the temperature was maintained
at 160.degree. C., the polytetrafluoroethylene sheets on both sides
were then sucked in vacuo to recover the thickness of the laminated
sheet up to 9 mm. Thereafter, the laminated sheet was cooled with
air for 3 minutes, and the polytetrafluoroethylene sheets were then
peeled off to obtain a heat-moldable composite sheet.
The resulting composite sheet was heated in an oven of 160.degree.
C. for 2 minutes, and then compressed with a mold of 30.degree. C.
at a compression force of 1 kg/cm.sup.2 for 1 minute to provide a
molded article. The mold had the thinnest portion of 3 mm and the
thickest portion of 8 mm. A curvature radius of a recessed portion
in the mold was 5 mm. The molded article was 1400 mm long and 1150
mm wide. A large number of small holes were formed in the molded
article on the polyethylene side. A curvature radius of a portion
in the molded article corresponding to the curvature radius, 5 mm
of the recessed portion in the mold was 5.4 mm.
The resulting molded article was measured for various properties in
the same way as in Example 15. The results are shown in Table
5.
EXAMPLE 17
Glass fiber chopped strands (length of 40 to 200 mm, monofilament
diameter of 9 to 13 micrometers) and polyethylene fibers (length of
50 mm, diameter of 30 micrometers) were fed at a weight ratio of
4:1 to a carding machine where the strands were opened into
filaments. Both were combined into a mat-like material. The
mat-like material was needle-punched at 30 portions per square
centimeter to obtain a mat having a thickness of 10 mm and a weight
of 500 g/m.sup.2. On both sides of the mat were laminated
polyethylene sheets (thickness of 150 micrometers, different MI:
0.5 & 15).
Glass fiber reinforced polytetrafluoroethylene sheets (thickness of
150 micrometers) were laminated on both sides of the resulting
laminated sheet, heated at 160.degree. C. for 3 minutes and
compressed with a flat press at a pressure of 10 kg/cm.sup.2 for 20
seconds. The compression was released and while maintaining the
temperature at 160.degree. C., the polytetrafluoroethylene sheets
on both sides were then sucked in vacuo to recover the thickness of
the laminated sheet up to 9 mm. Thereafter, the laminated sheet was
cooled with air for 3 minutes, and the polytetrafluoroethylene
sheets were then peeled off to provide a heat-moldable composite
sheet. A large number of small holes were formed in the surface of
the composite sheet on the side of the polyethylene sheet with MI
of 15.
The resulting composite sheet was heated in an oven of 160.degree.
C. for 2 minutes and then compressed with a mold of 30.degree. C.
at a compression force of 1 kg/cm.sup.2 for 1 minute to obtain a
molded article. The mold had the thinnest portion of 3 mm and the
thickest portion of 8 mm. A curvature radius of a recessed portion
in the mold was 5 mm. The molded article was 1400 mm long and 1150
mm wide.
A curvature radius of a portion in the molded article corresponding
to the curvature radius, 5 mm of the recessed portion in the mold,
was 5.5 mm. The resulting molded article was measured for
dimensional stability in the same way as in Example 2 and for
various properties in the same way as in Example 15. 90.degree. C.
for 100 hours), acoustical properties in 1000 Hz by a vertical
incidence method and an air-permeability were measured. The results
are shown in Table 5.
TABLE 5
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Heat Heat Flexural Flexural moldability distortion Acoustical Air-
Dimensional strength modulus (curvature resistance Properties
perme- stability Example (kg/cm.sup.2) (kg/cm.sup.2) radius) (mm)
(mm) (%) ability (%)
__________________________________________________________________________
15 25-27 3000-3100 -- 1.7 65 no -- 16 24-27 3000-3400 5.4 1.5 65 no
-- 17 25-30 3500-4000 5.5 -- 65 no 0.7
__________________________________________________________________________
Void ratios of the heat-moldable composite sheets and the composite
molded articles obtained in Examples 1 to 17 and Comparative
Examples 1 to 3 and the results (diameters and opening area ratios)
of microscopic observation of fine holes on the surfaces of the
composite molded articles are shown in Table 6.
TABLE 6
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Void ratio of Void ratio of the Microscopic observation of fine
holes on the heat-moldable composite molded the surface of the
composite molded article Example composite sheet (%) article (%)
[average value of 10 photos (50.times. magnification)]
__________________________________________________________________________
1 94 3 mm-thick portion: 82 Diameter of fine holes: 2-100 m 8
mm-thick portion: 93 (mostly 30-40 m) 2 94 91 (no film) 3 91 88
Diameter of fine holes: mostly 10-50 m (max. 300 m) Opening area
ratio: 3.4% 4 90 88 Diameter of fine holes: mostly 10-50 m (max.
300 m) Opening area ratio: 2.8% 5 95 90 (no film) 6 92 90 Diameter
of fine holes: mostly 10-50 m (max. 300 m) Opening area ratio: 5.6%
7 92 88 Diameter of fine holes: mostly 10-50 m (max. 300 m) Opening
area ratio: 5.4% 8 91 87 Diameter of fine holes: mostly 10-50 m
(max. 300 m) Opening area ratio: 4.2% 9 91 3 (back)
__________________________________________________________________________
portion: 73 Diameter of fine holes: 1-50 m 8 mm-thick portion: 90
Opening area ratio: 12.0% 10 94 3 mm-thick portion: 82 Diameter of
fine holes: 1-50 m 8 mm-thick portion: 93 Opening area ratio: 7.8%
11 92 2.5 mm-thick portion: 75 Diameter of fine holes: 1-50 m 5
mm-thick portion: 87 Opening area ratio: 18.2% 12 92 2.5 mm-thick
portion: 74 5 mm-thick portion: 87 13 92 90 laminated with a skin
14 92 90 (Fine holes are unclear.) 15 94 3 mm-thick portion: 82
Diameter of fine holes: 1-50 m 5 mm-thick portion: 93 Opening area
ratio: 7.4% (front) 0.6% (back) 16 " 3 mm-thick portion: 82
Diameter of fine holes: 1-50 m 5 mm-thick portion: 93 Opening area
ratio: 8.2% (front) 0.2% (back) 17 " 3 mm-thick portion: 82
Diameter of fine holes: 1-50 m 5 mm-thick portion: 93 Opening area
ratio: 6.9% (front) 0.9% (back
__________________________________________________________________________
Microscopic observation of fine holes on Comparative Void ratio of
the Void ratio of the the surface of the composite molded article
Example sheet (%) molded article (%) [average value of 10 photos
(50.times. magnification)]
__________________________________________________________________________
1 75 69 Diameter of fine holes: 10-50 m Opening area ratio: 0.4% 2
78 73 Diameter of fine holes: 10-50 m Opening area ratio: 0.6%
__________________________________________________________________________
* * * * *